“Should we be generous in peritonectomy?”: First prospective comparative analysis of total versus involved field parietal peritonectomy in CRS-HIPEC for peritoneal surface malignancies from COLO-rectal cancer—ISPSM collaboration study.

633 Background: Peritonectomy is the important components in management of peritoneal surface malignancies (PSM). Immunofluoresecne study done after involved field peritonectomy (IFP) has showed diease in areas not suspected on gross examination stressing the need for total parietal peritonectomy (TPP) for complete cytoreduction. The aim of this study was to assess the morbidity & mortality, recurrence pattern & oncological outcomes of extent of parietal peritonectomy with CRS & HIPEC for colorectal carcinoma. Methods: Patients with PSM from CRC underwent TPP or IFP with CRS- HIPEC. Pre & intraoperative data were analyzed with main focus on postoperative morbidity, mortality, recurrence pattern and oncological outcomes. Results: 40 cases of CRC of which four upfront, 17 interval and 19 recurrent cases. 19 & 21 patients underwent TPP & IFP respectively. Base line characteristics were comparable except median PCI (17 versus 12). TPP group had longer duration of surgery (11 vs 9), more blood loss (1300 vs 700 ml) increased diaphragmatic resections ( 46.2% vs 14.2%), multivisceral resection ( 46.2% vs 28.5%). Number of bowel resections, anastomosis and stoma were comparable. Overall TPP group had more G3-G5 morbidity (46.1% vs 35.7%) & surgical morbidity (30.7% vs 21.5%) . TPP group had increased pleural & intra-abdominal collections which needed intervention. With a median follow up of 30 months, DFS was significantly higher in TPP group (12months vs 8months, p < 0.01) and median overall survival was 21 months in IFP group (yet to be achieved in TPP group). TPP group had most of the recurrences in visceral liver & lung (50.0%) followed by peritoneal (37.5%) & nodal (12.5%) whereas in IFP it was peritoneum (42.8%), visceral ( 38.4%) & nodal (15.3%). Conclusions: It is the first prospective comparative study done on total parietal peritonectomy in PSM of colorectal cancer origin. TPP group had significantly higher DFS, with comparable postoperative morbidity. However, longer follow up and a prospective multi-institutional randomized study needs to be designed for more evidence of the same.